Summary, week 45/2012Influenza activity in the WHO European Region remains at a pre-season level, with several countries reporting sporadic detections of influenza A(H1N1)pdm09, A(H3N2) and type-B viruses. The influenza positivity rate is relatively stable, as is usual for this time of the year. The number of hospitalizations due to severe acute respiratory infection (SARI) remains stable, with none of the cases reported this week due to influenza.

Circulation of influenza viruses

Overall, a total of 95 specimens tested positive for influenza in week 45/2012, slightly more than in week 44/2012: 56 were type A and 39 were type B. Of the influenza A viruses, 33 were subtyped: 12 as A(H3) and 21 as A(H1)pdm09 (Fig. 1). Since week 40/2012, 311 influenza viruses from sentinel and non-sentinel sources have been typed: 206 (66%) were influenza A and 105 (34%) influenza B. Of the influenza A viruses 121 were subtyped: 64 (53%) as A(H3) and 57 (47%) as A(H1)pdm09.